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 1 2 3 
 
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 mi 
 
 
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 ON 
 
 
 
 LAURRNTIAN 
 
 OP 
 
 ROCKS 
 
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 Bi^Vi^LRIi^. 
 
 
 By Dh. GUMBEL. 
 
 
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 I'umbe! ' oil Kozooii Iro-n fhr primifivc Rocks ol' H.ivaria . 
 
 I 
 
ON THE 
 
 LAURENTIAS DOCKS OF BAVARIA 
 
 t 
 
 By Dr. Gumbel, 
 
 Director of the Geologiciil Survey of Bavaria; with a plate contaiuing 
 figures of two species of Eozoon. 
 
 (From the Caxadiam Natiualist /«/• JJect-mher, 186G.) 
 
 The discovery of organic remains in the crystalline limestones 
 of the ancient gneiss of Canada, for which we are indebted to 
 the researches of Sir William Logan and hi,s colleagues, and to 
 the careful microscopic investigations of Drs. Dawson and 
 Carpenter, must be regarded as opening a new era in geological 
 science. 
 
 This discovery overturns at once the notions hitherto commonly 
 entertained with regard to the origin of the stratified primary 
 limestones, and their accompanying gneissic and quartzose strata, 
 included under the general name of primitive crystalline schists. 
 It shows us that these crystalline stratified rocks, of the so-called 
 primary system, are only a backward prolongation of the chain of 
 Ibssiliferous strata ; the elements of which were deposited as 
 oceanic sediment, like the clay-slates, limestones and sandstones of 
 the paleozoic formations, and under similar conditions, though at 
 a time far more remote, and more favorable to the generation of 
 crystalline mineral compounds. 
 
 In this discovery of organic remains in the primary rocks, we 
 haii with joy the dawn of a new epoch in the critical history of 
 these earlier formations. Already, in its light, the primeval 
 geologic time is seen to be everywhere animated, and peopled with 
 new animal forms, of whose very existence we had previously no 
 suspicion. Life, which had hitherto been supposed to have first 
 
 * Editor's Xote.— Iu revising and preparing this Ibr the press, the 
 original paper has been considorably abritlgcil bv the omission of 
 portions, whose place is indicated iu the text. Some" explanatory notes 
 have also been added. — T. S. H. 
 
 '"_• •••• • 
 
 • • - • • 
 
2 
 
 UU.MIJKL— ON LAUHKNTIAN HOC'KW. 
 
 appeared in the priiii..rtlial division iA' the Silurian period, id now 
 seen to bo ininieasunihly lon-rtliencd beyond its former limit, and 
 to embrace in its domain the most ancient known portions of the 
 earth's crust. It would almost neem as if orjranic life had been 
 awakened wimultaneously with the solidification of the earth's 
 
 Ci'Ust. 
 
 The <,'reat importance of this discovery cannot bo clearly 
 understood, unless wo first consider the various and conflicting 
 ophiions and theories which had hitherto been maintained 
 concerning the origin of these primary rocks. Thus some, who 
 consider them as the first-formed crust of u previously niolten 
 globe, regard their apparent stratification as a kind of concentric 
 parallel structure, developed in the progressive cooling of tlie nntss 
 from without. Others, while admitting a similar origin of these 
 rocks, suppose their division into parallel layers to bo due, like the 
 lamination of clay-slates, to lateral pressure. If we admit such 
 views, the igneous origin of schistose rocks becomes conceivable, 
 and is in fact maintained by many. 
 
 On the other hand, we have the school which, while recognizing 
 the sedimentary origin of these crystalline schists, supposes them 
 to have metamorphosed at a la^er period ; cither by the internal 
 heat, acting in the deeply buried strata; by the proximity of 
 eruptive rocks; or finally, through the agency of permeating waters 
 charged with certain mineral salts. 
 
 A few geologists only have hitherto inclined to the opinion that 
 these crystalline schis.s, while possessing real stratification, and 
 sedimentary in their origin, were formed at a period when the 
 conditions were more favorable to the production of crystalline 
 materials than at present. According to this view, the crystalline 
 structure of these rocks is an original condition, and not one 
 supcrmduccd at a later period by metamorphosis. In order 
 however to arrange and classify these ancient crystalline rocks, it 
 becomes necessary to establish, by superposition or by other 
 evidence, differences in age, such as are 'ognized in the more 
 recent stratified deposits. The discovery of similar organic 
 remains, occupying a determinate position in the stratification, in 
 different and remote portions of these primitive rocks, furnishes a 
 powerful argument in favor of the latter view, as opposed to the 
 notion which maintains the metamorphic origin of the various 
 minerals and rocks of these ancient formations ; so that we may 
 regard the direct formation of these mineral elements, at least so 
 
 1 
 
 • 
 
 / 
 
 A' 
 
i 
 
 / 
 
 Ji. 
 
 0I;MBEL— UN LAIIRENTIAN IlOCKS. 3 
 
 tar nn these fo.s,silifl.rou.s pri.nary lhnesto,.eH are concerned, an an 
 Crftabli.shed tact. . ■ . "•• 
 
 So early «« 185;}, .fW invo.ti^ratin,,^ the prin.i.ive rooks of 
 eastern Bavaria, wind, arc cunncctod \viti, tho.so ,.t the JJohc u.ian 
 forest, r expressed the „pi,Mon that, nMunv^h cru, live nmsscs of 
 ^'nnute and si.Mil.r r-.ks oecur in that region, the p.ei.ss was of 
 Hcdnncntary ori.ui,., ,„k1 divisible int.; neveral ll.rn.ati.m.s. I at 
 that tin.e endeavored to .separate these crystalline schists into 
 three f^reat divisi.M.s. the phyllade.s, .ho .nica-schists, and the 
 fineiss forniation, of which the first was the y.mnaest and the last 
 the oldest ; all these formations havinj; essentially the same dir. 
 and strike. ' 
 
 These results, obtained from very detailed ue<.louical and topo- 
 .uraphical reseaivhcs, were subsc.,u(mtly m.,re fully set forth in the 
 Nurvey of the (Jeolo,!.'y of Kastern Bavaria, (Book IV.. p. 219 rf, 
 seq.) ; where I endeavored to assiun loeal names to the subdivisions 
 of the primitive rocks of that re-ion. Be-innin- with the more 
 recent, I distin,<rnished the following formations : 
 
 1. Hercynian primitive clay-slate. 
 
 2. Hercynian mi, 
 ;5. Hercynian gnt 
 4. Bojian gneiss. 
 
 In some cases, within 
 out still smaller snbdivi.siui 
 
 y gneiss svsteir. 
 
 .is, I even succeeded in traoin" 
 i'as in this w>>y established that 
 acfinite and distinct kinds of rocks, as for example hornblende- 
 slate and mica-slate, may replace each other and, as it were, pa.ss 
 into each other, in different parts of the same horizon. 
 
 After Sir Iloderick Murchison had established the existence of 
 the fundamental gneiss in Scotland, and recognized its identity 
 with that of the Laurentian system of Canada, he turned his 
 attention to the primitive rocks of Bavaria and Bohemia. My 
 researches and my communications to him disclosed the iu,portant 
 fact that these rocks belong tc the same series as the oldest 
 formations of Canada and of Scotland. On one point only was 
 there an apparent difference of opinion between Sir Iloderick and 
 myself; which was that he was disposed to look upon the who'o 
 of the gneiss of the Hercynian mountains as constitutino but a 
 single formation, corresponding to the Laurentian gnei.ss of Canad.a 
 and of Scotland ; while I had endeavored to 'distinguish two 
 divis:')ns, the newer grey or H^rcyniau gneiss, and the older red 
 
4 «JI -MFJLI ON LAURENTIAN ROCKW. 
 
 or vari.-at.a. which I callod the Hoji.n pnoi < This diffcrenco 
 of ..jMiMu.i IS h^^vcvet• at onco removed by the remark that I did 
 not intend to niiantuin in the older p.eiss the existence of a 
 forniatmn more anei(>nt than the fundamental ^noiss of Scotland 
 nor yet, to asHmihite the newer or ^rey gueis.s to the more rcctmt 
 or so-eullod n.etan-orphic serios, which, according,' to Sir Koderiek 
 nny be dearly distinguished in Scotland fron; the Laureutiaii 
 ^'noiss. 
 
 [This newer uneissic formation of the IHol:and8 is, occordinL' 
 to Murchison, Kamsay and others, of Lower Silurian a-'o Our 
 auth...- simply claims to have established a division in the proper 
 . J.aurentian rocks of Bavaria and Bohemia. It will be .eon 
 from the recently published maps of the Laurentian rej^ion of the 
 Ottawa, that Sir William Lo^an there distin-uishe.; three grert 
 limestone formations, by wlueh the enormous muss of Luuroutiar. 
 p.eiss IS s , Mrated into four divisions. One or two of the upper 
 ones of these may be eventually found to correspond to the j^rey 
 Ilercynian -nciss of Bavaria, which is there uccon.panied by the 
 Lozoon C.-'nadensc, a fossil so far us yet known characterizing the 
 "i-hest of the three Laurentian limestones.. This grey .rneiss 
 uf Bavaria appe-irs to be lithologically distinct from the Lubmdor 
 (or I pper Laurentian) series; nor do we find in the present 
 niemou- of (Jumbel, any clear evidence of the occurrence either of 
 
 this, or of the Huronian system, in Bavaria. T. S, IJ 
 
 After citing in this connectio.i Sir W. E. Loga'n's observations 
 on these ancient formations, which are shown, by the results of the 
 Canadian Survey, to reprcocnt three great systems of sedimentary 
 rocks, formed under conditions not unlike those of more modern 
 
 formations, our author observes: ] 
 
 Accepting these views of the older Canadian rock.s, it would 
 naturi)lly follow that organic life might be expected to' reach back 
 much farther than the so-called primordial fauna of Lower 
 Silurian age, and to mark the period hitherto designated as Azoi- 
 Guided by these ideas, the geologists of Canada zealously sou-^ht 
 for traces of organic life in the primitive rocks of that country 
 Dr. Sterry Hunt had already concluded that it must have existed 
 m the Lauren., n period, fiom the presence of beds of iron ore 
 and of metallic sulphurets, which, not less than the occurrence of 
 graphite, were to him chemical evidences of an already existing' 
 vegetation, when at length direct evidence of life was obtained by 
 the discovery of apparently organic forms in the great beds of 
 
 
OUMBEI,— ON LAUR. NTIAN IKUM, . 5 
 
 ciystalline limcMtnnc which occur in the Lnurc itiaa tysteni. Such 
 
 wore colu'ctod in iHfjH. by Mr. J. McMu. .r, inm the Grand 
 
 (^iihm.ct on tho Ottawa Kivcr, and wcro chscrvcd hy Sir Wni. 
 
 Locran torcscnibb closeiy «ii„ilar specimens obtained by Dr. lames 
 
 WilH(^n in Bur^'c-^s. a few years previously. I-i 1S59, Sir Wm. 
 
 Lnjian first expressed Km opinion that these masses, in whicli 
 
 pyroxene, seipentine, and an allied mineral, aUernatetl in thin 
 
 l.'iyers, with carbor.ate of lime or dolomite, were of ort;anic orif^in ; 
 
 and in IHOl' he reilerated this opir.ion in En-land, without 
 
 however bein- able to convince the En-lish -eoloirists, Il.nisay 
 
 excepted, of the correctness of his views. Soon after this, 
 
 however, the discovery of other and more perfect specimens, at 
 
 Granville, furnisliod decisive proofs of the organic nature of these 
 
 Hinjiular fossil- . 
 
 Tlio careful and admirable investifrations of ]j..wson and of 
 Carpenter, to whom specimens of the rock wore confided, have 
 placed beyond doubt tlie organic strr v;- -.f those remains, and 
 confirmed the i.nportant fact that the. ■ ancient Laurentian lime- 
 stones abound in a peculiar organic fossil, unknown in more recent 
 formations, to wlilcli has been given the name of Eozoon.=>= 
 
 * 
 
 * 
 
 * 
 
 * 
 
 The researches of Storry Hunt on the mineraloglcal relations of 
 
 the Eozoon-bearing rocks, lead him to the in)portant conclusion 
 
 that certain silicates, namely serpentine, wiiite pyroxene, and 
 
 loganito, have filled up the vacant spaces left by the disappearance 
 
 of the destructible animal matt.T of the sarcode, the calcareous 
 
 skeleton remaining more or kws unchanged. If, by the aid of 
 
 acids, we remove from such specimens the carbonate of lime, (or, 
 
 in certain cases, tlie dolomite whicIi replaces it,) there remains a 
 
 colierent skeleton, which is evidently a cast of the soft parts of the 
 
 Eozoon. The process by which the silicates have been introduced 
 
 into the empty spaces corresponds evidently to th.-it of ordinary 
 
 silieification through the action of water. It is to be noted that 
 
 Hunt fcund serpentine and pyroxene, side by side, in adjacent 
 
 chambers, and even sharing the same cliamber between them; 
 
 thus affording a beautiful proof of their origin through the 
 
 * ITero follows, in the original, a lenj^thoucd analysis of the memoirs 
 of Men.srs. Logan, Daw.son, Carponter, and Uuut, i,u])lish("cl in tho 
 Quarterly Journal of the Geological Society of London, and already 
 reprinted in the Canadian Xaturalist. 
 
♦) 
 
 (JUMBEI ON LAURENTIAN ROCKS. 
 
 infiltration of aqueous solutions, wliile the Eozoon was vet 
 Ki-uwiiig, or shortly after its death. -i-- * % 
 
 Hunt, in a very in^irenious manner, compares thi. foruiation and 
 deposition of serpentine, pyroxene, and lo-anite, with that of 
 Klauconite, whose formation has gone on uninterruptedly from the 
 Silunan to the Tertiary period, and is even now takin. place in 
 the depths of the sea ; it being well known that Ehrenber-^ and 
 others have already sliown that many of the grains of glauc"onite 
 are oasts of the interior of foraniiniferal shells. I„ the lioht of 
 tlus comparison, the notion that the serpenti.ie, and such like 
 minerals of the primitive limestones have been Ibrmed in a similar 
 wanner, in the chambers of Eozoic foraminifera, loses any traces 
 of improbability which it might at first seem to possess. -'K ^f^ 
 My discovery of similar organic remains in the serpentine- 
 limestone from near Passau was made in 18G5, when I h-id 
 returned from my geological labors of the summer, and received 
 the recently published descriptions of Messrs. Lo-an, Dawson etc 
 Small portions of this r..ck, gathered in t!ie pn-ress of' the 
 geological survey in 1854, and ever since preserved in my 
 collection, having been submitted to microscopic examination 
 confirmed in the most brilliant manner the acute judgment of the 
 Canadian geologists ; and furnished palontological evidence that 
 notwithstanding the great distance wlm-h separates Canada from' 
 Bavaria, the equivalent primitive rocks of the two regions are 
 characterized by similar organic remains; showing at the same 
 time that the law governing the definite succession of organic life 
 on the earth is maintained cvtm :.i these most ancient formations. 
 The fragments of serpentine-limestone or ophicalcite, in which I 
 first detected the existence of Eozoon, were like those described in 
 Canada in which the lan.ollar structure is wantin- and offer 
 only what Dr. Carpenter has called an acervuline structure. For 
 fiirtiier confinnatii-n of my observations, I deemed it advisable 
 through the kindness of Sir Charles Lyell, to submit .specimens of 
 the Jiavariau rock to the examination of that eminent authority, 
 Dr. Carpenter ; who, without any hesitation, declared tium to 
 contain Eozoon. 
 
 This fact being established, I procured from the quarries near 
 Pas,sau as many specimens of the limestone as the advanced season 
 ol the year would permit ; and, aided by my dilioent and skilful 
 assistan..i Me.ssrs. licber and JSchw .ger, exami.ed them by the 
 methods iudieatr.! bv Messrs. Dawson aud (Carpenter. Tn this 
 
' 
 
 * 
 
 GlIMBEL— ON LAURENTIAN ROCKS. 7 
 
 way I soon convinced myself of the general similarity of our 
 organic remains with those of Canada. Our examinations were 
 made on polished sections and in portions etched with dilute nitric 
 acid, or, better, with warm acetic acid. The most beautiful 
 vesults were however obtained by etching moderately thin sections, 
 so that the specimens may be examined at will either by reflected 
 or by transmitted light. 
 
 The specimens in which I first detected Eozoon came from a 
 quarry at Steinhag, near Obernzell on the Danube, not far from 
 Passau. The crystalline limestone here forms a i hss from fifty 
 to seventy feet thick, divided into several beds, included in the 
 gneiss, whose general strike in this region is N.W., with a dip of 
 40--G0- N.E. The limestone strata of Steinhag have a dip of 
 45° N.E. The gneiss of this vicinity is chiefly grey, and very 
 sihcious, containing dichroite, and of the variety known as 
 dichroite-gueiss ; and I conceive it to belong, like the aneiss of 
 Bodenmais and Arber, to that younger division of the primitive 
 gneiss system which I have designated a,s the Hereyniau gneiss 
 formation ; which both to the north, between Tischenreuth and 
 Mahring, and to the south, on the south-west of the mountains 
 of Ossa, is immediately overlaid by the mica-slate formation. 
 Lithologically, this newer division of the gneiss is characterized by 
 the predominance of a grey variety, rich in quartz, Avith black 
 magnesian-mica and orthoclase, besides which a small quantity of 
 oligoclase is never wanting. A farther characteristic of this 
 Hercynian gneiss is the. frequent intercalation of beds of rocks 
 rich in hornblende, such as hornblende-schist, amphibolite, diorite, 
 syenite, and syenitic granite, and also of serpentine and granulite! 
 Beds of granular limestone, or of calcareous schists are also never 
 altogether wanting; while iron pyrites, and graphite, in lenticular 
 masses, or in local beds conformable to the great mass of the gneiss 
 strata, are very generally present. 
 
 The Hercynian gneiss strata on the shores of the Danube near 
 Passau are separated from the typical Hercynian gneiss districts 
 which occur to the north, on the borders of the Fichtelgebirge and 
 near Bodenmais and Arber, by an extensive trac^t, partly occupied 
 by intrusive granites, and partly by another variety of gneiss. 
 These Danubian gneiss strata are not seen to come in contact 
 with any newer crystalline formuiion, but towards the south 
 
 fire 
 
 conce 
 towards 
 
 led by the tertiary strata of the Danubian plain ; while 
 the N.W. they arc in part cut oflP by granite, and in part 
 
8 
 
 'U;.MBEL— ON LAURENTIAN KOCKS. 
 
 I 
 
 replaced by those belts of ..neiss wlnV^ n« 
 
 ridge of ,h„ p«,H „„, ,£:;:'z : Til? r'' 
 
 ^i.ioc ,1, s d , f , "■'" ■"""'■"' •■"■" 'W*-! "' 'W-" view, 
 
 '" "'°.'' '"" "»ly l«-«e"ts .. general i-csfmblaiice to tl,^ 
 
 . .,,,,*, ,,'''"''k^ ■";■'"■' "'""■" "'" Danube), occu,, a» 
 
 :;;:::;^;;=:o,:;-zt::::;;:;;:;.:;f/-- 
 
 fVip s,,-;i-<, A \' n' . "^ "■■^"I'liiii; ci i.iuit ruiiiiinir a Oii'' 
 
 tl- J 1 iMl . bro„,d,t „,,, „„J .o„„.» ,o „v,.,lio ,l,e you,,.,,,? 
 
 If t H fn„ ' ^ "' "■"" ''>''"^'» "'«' '"""""tie pyrites 
 
 «.-aplu.eoccur.sl,oro „„,„,;:' '" '","" " '"' ' ^'""^ 
 
 .iiiuoM all the strata, and m some pla 
 
 m 
 
9 
 
 (JUMBET — ON LAURENTIAN ROCKS. 
 
 such quantities that it is profitably extracted, and is larsrcly used 
 for the manufacture of the famous I'assau crucible^'. In all of 
 the numerous graphite mines, the uniform intcrstratification of 
 bands and lenticular masses rich in graphite with the uneiss 
 is here distinctly marked. A similar arrangement is seen in the 
 sulphurets of iron, which are more abundantly disseminated in the 
 more hornblendic strata. . The localities of porcelain-earth or 
 kaolin are in like manner confined to the strike of the gneissic 
 strata; and are generally contiguous to certain interstratitied 
 granitic and syenitic bands, rich in feldspar. Its frequent 
 association with porcelain-spar, (probably nothing more than 
 a chloriferous scapolite or anorthite,) indicates that this mineral 
 has played an essential part in the production of the kaolin'. The 
 presence of chlorine in tliis mineral is ] •gbly significant, and 
 suggests the agency of sea-water in its production. 
 
 Of particular interest, from their mineral associations, are three 
 or^ more parallel bands of crystalline limestone of no great 
 thickness, which occur conformably interstratifieu with the gneiss 
 of the hills near Passau. They begin near llofkirchen, and 
 extend north and south, from along the Danube as far as the 
 frontier, near Jochenstein, where the Danube leaves Bavaria. 
 These separate limestone bands, although exposed by numerous 
 quarries, cannot be followed uninterruptedly, being sometimes 
 concealed, and sometimes of insignificant thickness. 
 
 * * .i. ' ^ * >|c 
 
 The large quarry of Steinhag already described, from which I 
 first obtained the Eozoon, is one. The enclosing rock is a grey 
 hornblendic gneiss, which sometimes passes into a hornblende- 
 slate. The limestone is in many places overlaid by a bed of 
 hornblende-schist, sometimes five feet in thickness, which separates 
 it from the normal gneiss. In many localities, a bed of serpentine, 
 three or four feet thick, is interposed between the limestone and 
 the hornblende-schist ; and in some cases a zone, consisting chiefly 
 of scapolite, crystalline and almost compact, with an admixture 
 however of hornblende and chlorite. Eeluw the serpentine band, 
 the crystalline limestone appears divided into distinct beds, and 
 encloses various accidental minerals, among which are reddish- 
 white mica, chlorite, hornblende, tremolite, chondrodite, rosellan, 
 garnet, and scap,>lito arranged in bands. In several places the 
 "s mingled vith serpentine, grains or portions of which, often 
 e size of peas, are scattered through the limestone with 
 
 of 
 
10 
 
 aUMBEL — ON LAURENTIAN ROCKS. 
 
 :ipparent irregularity, fjiving rise to a beautiful v^ariety of opliical- 
 cite or serpentine-marble. These portions, which are enclosed in 
 the limestone destitute of serpentine, always present a rounded 
 outline. In one instance there appears, in a hi<:;h naked wall of 
 limestone without serpentine, the outline of a mass of ophicabite, 
 about sixteen feet lonu; and twenty-five feet hi-ih, which, rising 
 from a broad base, ends in a point, and is separated from the 
 enclosing limestone by an undulating but clearly defined margin, as 
 already well described by Winuberger. This mass of ophicalcite 
 recalls vividly a reef-like structure. Within tliis, and similar 
 masses of ophicalcite in the crystalline limestone, there are, so far 
 as my observations xw 1S5-4 extend, no continuous lines or 
 concentric layers of serpentine to be observed, this mineral being 
 ahvays distributed in small grains and patches. The few 
 apparently regular layers which may be observed are soon 
 interrupted, and the whole aggregation is irregular. [This is 
 well shown in plates II. and III. in the original memoir, which 
 recall the acervuline portions, that make up a large part of the 
 Canadian specimens of Eozoon. — Kds.] 
 
 The numerous specimens which w^^re subse(iucntly collected, at 
 the commencement of tlie winter, show, throughout, this irregular 
 structure, which seems to characterize the Bavarian specimens of 
 Eozoon, as is in part the case in those from Canada. It is true 
 that small lenticular masses or nodules, consisting chiefly of 
 scapolite, measuring fifty by twenty millimeters, and even nuich 
 more, are often met with, around which serpentine is arranged in 
 a concentric manner ; but even here the serpentine is in small 
 cohering masses, and not in regular layers ; nor could I, after 
 numerous examinations of fragments of such masses, satisfy 
 myself whether I had to deal with the commencing growth of an 
 Eozoon, or merely with a concretionary nniss; since the granular 
 structure of the scapolite centre could never be clearly made out. 
 Moreover the occurrence of these nodules, arranged in a stratiform 
 manner, is opposed to the notion that they are nuclei of Eozoon, 
 although in the parts around these nodules I could sometimes 
 distinctly observe tubuli, canals, and even indications of a shell-like 
 structure. 
 
 The portions of serpentine in the ophicalcite occur of very 
 various sizes, from that of a millet-seed to lumps whose sections 
 measure fifteen by six or eight millimeters. But I tliink I can 
 detect within certain lines, (which are not, it is true, very well 
 
GTJMBEL — ON LAURENTIAN ROCKS. 
 
 11 
 
 defined,) chains of serpentine grains, of nearly equal size, coi^nected 
 with each other. When by means of acids the liu.e is removed 
 from these arr-j-e-ates, a perfectly coherent serpentine skeleton is 
 m alUases obtained, which may be compared to a piece of wood 
 perforated by ants. * H< ;|s sf« * 
 
 The surface of the serpentine jrrains is rounded, pitted, and 
 irregular; plane surfaces and straight lines are rarely to be seen. 
 Even when dilute nitric or acetic acid lias been used to remove 
 the lime, a white down-like; coating is fre(iuently ibuiid on tlie 
 serpentine, which does not answer to the nummuline wall of the 
 calcareous skeleton. In many cases, where the lime is very 
 crystalline, and the more delicate organic structure obliterated, 
 small tufts of radiated crystals, apparently hornblende or tremolite, 
 are seen resting upon the serpentine. These crystals, when seen 
 in thin sections, by transmitted light, may easily give rise to . 
 errors; their formation seems to have been possible only where the 
 calcareous skeleton had been destroyed, and crystalline carbonate 
 of lime deposited iu its stead ; during which time free space was 
 given for the xbrmation of these crystalline groups. In very 
 many cases tin re are seen, by a moderate magnifying power, (in 
 the residue fro.a acids) deposits of small detached cylindrical 
 stems, with some I.'rger ouey, consisting of a white matter insoluble 
 ia acids. These appem- to be the casts of the tubuli which 
 penetrated the calcareous skeleton, and of the less frequent stolons, 
 as will be described. 
 
 The serpentine in these sections never appears quite homo- 
 geneous, but exhibits, on the contrary, irregular groups of small 
 dark-colored globules disseminated through the mass, without 
 however any definite indications of organic form. Still more 
 frequently, the serpentine is penetrated by irregularly reticulated 
 dark colored veins, giving to the mass a cellular aspect. 
 
 In certain parts of the serpentine, however, parallel lines, groups 
 of curved tube-like forms, and oval openings, clearly hidicate an 
 organic structure like that of the Canadian Eozoon. The finely 
 tubulated nummuline wall of the chambers, wliieli was discovered 
 by Carpenter, and the casts of whose tubuli appear in tho 
 decalcitied specimens from C;...ad-i as a soft white velvet-like 
 covering, could only be found in a few isolated cases in the 
 Bavarian specimens, but wa.s clearly made out in a few fragments. 
 (PI. I., 4.) The somewhat oblique section shows the openings 
 of the minute tubuli. 
 
12 
 
 OTTMnET- — OS LAITRENTIAN ROCKS. 
 
 It should be remarked that the .serpentine at Steinliat; occurs, 
 not only replacing' the sarcodo in the carbonate of lime of 
 tlie Eozoon, but also lbrmin<v layers over the limestone strata, 
 and moreover filling' up lar<j;c and small crevices and fissures, 
 which have notliin,!,' at all to do witli the oriranic structure. 
 Especially worthy of notice are the plates of fibrous serpentine, 
 or chrysotile, often from five to ten millimeters in diameter, 
 which are found extending in unbroken lines through the compact 
 serpentine. 
 
 The color of the serpentine presents all possible shades, from 
 blackish green, to the palest yellowish green tint. Where it has 
 been exposed to the weather, the serpentine has become of a pale 
 brownish green, and appears changed into gynniite. The different 
 tints are arranged in zones, and seem to mark different periods of 
 growth. The carbonate of lime which is interposed among the 
 grains of serpentine in the specimens from Steinhag, is either 
 distinctly crystalline, or apparently compact. In the first case, no 
 organic structure can be perceived ; thin sections of tlic crystalline 
 portions show only intersecting parallel lines; and in etched or 
 entirely decalcified specimens, no clear evidence of the fine 
 canal-system of the skeleton can be observed. These crystalline 
 portions often alternate with others which are compact and but 
 feebly translucent. In thin sections of these compact parts, the 
 rounded forms of the delicate tubuli are very clearly discerned, 
 provided the section is at right angles to them. In etched 
 specimens, viewed by reflected light, these tubuli are seen to 
 branch out in the form of tufts, exactly as described and figured 
 by Drs, Dawson and Carpenter. 
 
 These branching and ramified tubuli rest upon the serpentine 
 granules, and seem by anastomosis to be connected with adjacent 
 groups. The diameter of these tubuli is from lufni to roSff 
 millimeters. They arc easily distinguishable from the delicate 
 groups of crystals, which are also sometimes found implanted in 
 the serpentine, by the nearly uniform thickness throughout their 
 whole length ; by their extremities, which are always somewhat 
 crooked ; and by thoir pipe-like form. The latter are never 
 ramified ; have a fibrous aspect ; and are a 'ways straight, and 
 terminate in a point. (PI. I., figs. 1, 2, 3.) 
 
 Here and there arc observed larger tubuli, which, so far as my 
 observations extend, are always isolated, and nearly or quite 
 parallel. (PI. I., fig. 1.) Their diameter is about t^o millimeters, 
 
OUMBEL— ON LAUUENTIAN ROCKS. 
 
 13 
 
 and they not improbably roi)re8ent tliose stolons or connecting 
 channels with which Carpenter has made us acquainted. 
 
 In the decalcified specimen.;, delicate very slender string-like 
 leaflets were very fre(,uently observed, stretched between" the 
 serpentine granules ; but they presented no discernible organic 
 structure, and are perhai)s only the casts of small crevices. More 
 remarkable are the numerous canals filled with carbonate of lime, 
 whicli traverse the serpentine granules, and at the surface of these 
 are expanded into funnel shapes. They appear to represent cross 
 connections between the calcareous skeleton. 
 
 As my object at present is merely to shew the presence, in the 
 primitive limestones of Bavaria, of forms corresponding to the 
 Canadian Eozoon, I will not dwell longer on these^various 
 appearances mct-with in the mioroscopi ml examinations, nor on 
 the peculiar cellular structures observed in the carbonate of lime. 
 I will, for the same reason, only mention a specimen which cxliibits,' 
 by the side of a curved main tube, a number of secondary tubuli,' 
 and farther on a parallel layer of fibres; and also another radiated 
 form which resembles a section of a Bryozpon. It is sufficient to 
 draw attention to the fact that, in addition to Eozoon, there are 
 otlier organic remains in these crystalline limestones. There 
 remains however to be noticed a phenomenon of some importance. 
 When the lime is removed by nitric or acetic acid from the 
 interstices of the serpentine granules, there may be observed, on 
 gently moving the liquid, extremely delicate membranes, that 
 separate themselves from the serpentine grains, (which they 
 covered thickly, as with a tine white down,) and now remain 
 swimming in the liquid, so that they can readily be separated, 
 by decantation, from a nmltitude of heavier particles, which' 
 having also detached themselves from the serpentine mass, accu- 
 mulate at the bottom of the vessel. These consist in .great part of 
 indistinct mineral fragments, and of small crystalline needles, 
 together with distinct cylindrical portions, which are tlie broken 
 tubuli of the Eozoon. Besides these are, here and there, distinctly 
 knotted stems or tubules, {Vl I., figs. 5, a and h,) which I dare 
 not suppose to belong to Eozoon. Various other fragments of 
 tubuli are also associated with these. 
 
 The delicate flakes, which can be obtained by evaporating the 
 liquid in which they are suspended, shew, under a magnifying 
 power of 400 diameters, a membranous cliaracter, and peculiar 
 structures, which seem to be undoubtedly of organic origin. 
 
14 
 
 Their forms are best undo 
 
 OTJMBEL-ON LAURENT[A^ UocivS. 
 
 ;r.stood by tlie fi. 
 
 --10 examination of the finn Ju, '' "'.V'^'"''^'* **' "' ''"'' '" "°<i <^- 
 various ,,n,„ary c™. „' „ '^ ™.I,k., ,W„„ „, .solution „f 
 
 "-.ono.s in ...0 vl^:;:;;:; ,:'■■;' -'7"'i- o'--..ii.r 
 these sr«in,e„s eolloclcd A,; ' '"'" """'"^ «"" 
 
 twelve ,.o,.,r, .si r e elM '' '"^ "*''''""'™' '^='''"'"'»tio„s 
 
 of their l,„ldi,, „,.,,,„;, "1 :„, t '*'■"'""' '" ""= P»»»iWlity 
 at le»a traced of IZ ' ™»»'='J=<"'"weve,- in deteeting 
 
 from Kadin. ;,nVste ;l r^: r - '^".^'"" (««■ 3,) and 
 flo.M » quarry near ,Sri,r in bl r""™ "* "P'"'""'"''" 
 
 floMenkr „,, ,fn,o„. ' tbl ' V "TC '"""'*'™ K™'aau and 
 
 unequivocal' eviZe "oV ir V 'I "^ f^,' '"'"■^'"' 
 
 h« received .s„ecin,eus „f '. ""nr ? """h^'to^ n.oreover 
 strata at Krun.'au in wlnVh T < """""' f™"' "'^ »»»"= 
 
 of Ko.„„„. To"', : ," \"'- ?;"p™'r '"" *"" "'" i'-™» 
 
 nearsehwar.hae,:tr:i"; ;;:;„s^jt::'r-- -^' 
 
 ™..iiar .strata „ea P , fi! "t ! T "' ^™"'"'' -'"' ">« 
 the ,reat .ranit^ ,:;•,,! n "*'* '.""^^ "™ ""'^ -P-«tod by 
 a stni fiu-ther pro f L '."'■'"■""•'';"' '''""' ■**'" "'"» "b'"!" 
 whole ran„^ of'™ , , v ol" :/? °' ?'"'"';'■= "'™"«"™' *e 
 t.-c p.arallens„, „■;■ ^^ ^^^::i ^ ^";-;™;:' .• a-O.of 
 system of Canada 7 il.i i .i, „ "" ""= J^aurentian gne ss 
 hesitation »/,"!: 7/ ""*"'" *'"" "" ""V. "ithou 
 
 Krbendorf, from whiel, a f, B'"Wrab, not far fr„„, 
 
 however a re, ais "e J fc! '''^'''''T"™ '" ''»"''• 'f-y were 
 
 of horublond LiZe . r°" ""' ''"°'"'"'' ^"^ A''-' 
 
 R,-:,_ ,, '"'"'°"'™."ave me no traceofor..a„ie remain 
 
 Be.d. the^e nu.esto„e= of the Hercyniao gneiss, there L Znd 
 
 .. 
 
(Jl'MIlKL— UN LAIRKNTIAN ROCKH. 
 
 15 
 
 .. 
 
 m Haviiria nnofhor roiuurkHblo dop.),sit cf crvstalliiio linicHtoiie, 
 included in tho Eiorcynian primitive clay-,slatc''.sorieH on the .south 
 and soutli-ea8t border of the Fiehtel-ebir-e, in the vieinity of 
 Wu.useidel. This clay-shite Ibrn.atioi,, as we have ah-eady nhewn 
 overheH the Ilercynian ^uoIxh and n.iea-shite series, and is 
 nnn.ediately heneath the priinnrdial zone of the Lower Silurian 
 strata met with in the Fiehteloobirov. Tt would tlms seenj to 
 correspond with the Cambrian rocLs ol' >Vales, and with th- 
 Huroiuan e-ystem of Canada, as Sir lloderick Murehison has 
 already su-ested. This view is confirmed by Fritzsch's discovery 
 of traces of annelids in the -rauwacke of Przibram, and by the 
 occurrence of crinoidal stems and fl.raminiferal forms, aceordin- to 
 Keuss, in the limestone of the primitive elay-slates of ]»aukratz, 
 near lleichenstein. Thus our Hercyni.n mica-slate, with certain' 
 hornblendic strata and chloritie schists belon-in- to the same 
 horizon, would occupy a strati-raphical position* similar to the 
 Labrador series, or Upper Laurentian, of Canada. 
 
 The crystalline limestone of tho Fichteloebir^e forms in the 
 primitive clay-slu. two nearly parallel bands, which I conceive to 
 be the outcrops of one and the same stratum, on tlie opposite sides 
 of a trouo'h. It presents several j)arallel beds separated by inter- 
 vening beds of the conformable clay-slate. 
 
 The limestone strata near Wunseidel dip from 50"^ to 75° S.E. 
 and sometimes attain a thickness of 350 feet. They are in many 
 places dolomitic. =i= ^^' ^i^ :f: Spathic iron, 
 
 in nests and disseminated, characterizes this rock, and by its 
 decomposition pives rise to the valuable deposits of brown liematite, 
 wliich are worked along the outcrop of the limestone band! 
 Among the other minerals may be mentioned graphite, in crystal- 
 line plates, and also in small round grains and rounded compact 
 masses in the limestone ; besides which it frequently enters into 
 the composition of tho adjacent clay-slate, givmg rise to a 
 plumbaginous slate. Fluor-spar, chondrodite, tremonte, common 
 hornblende, serpentine, cubic and magnetic pyrites, are among the 
 minerals of the limestone. Quartz secretions are also met with, 
 but are evidently of secondary origin. The hornblende forms 
 rounded patches, remarkable twisted stripes, and banded parallel 
 layers, often of considerable dimensions, as in the specimens from 
 Wunseidel, whieli exhibit sheets of hornblende of from five to 
 fitleeii millimeters, separated by limestone layers of from fifteen to 
 twenty millimeters in thickness. My examinations of the specimens 
 
UJ 
 
 (lUMBEL — ON LAURENTIAN ROCKS. 
 
 of this nature, in my c(tlloctioii, have not enabled nie to connect 
 these lionibleiide hiyors with orj^anic strutiure, nor to discover 
 any traces of Kozoon in the hij'hly crystalline limestotie. 
 
 The result of my examinations of specimens of the limestone 
 containiiif^ serpentine from the (juarries near Wunseidel, from 
 Thiersheim, and from between llolienberfj; and the Hteinberg, were 
 however more successful. Fra^inoiits of the rock from near 
 lluheiiberi; show irregular greenish stripes, which are made up of 
 parallel undulating lamiuic, or of elongated grains. This banded 
 aggregate is a granular mixture of carbonate of lime, serpentine, 
 and a white mineral, insoluble in acids, which appears to bo 
 a variety of linrnblende. The grains of this aggregate have 
 generally a diameter of iV millimeter. 
 
 When examined in thin sections, the jalcareous portions appear 
 for the most part sparry, and traversed by straight intersecting 
 lines, (IM. 1, lig. 7 <i,) t»r divided into cellular spaces by small 
 irregular bands, which, after the surface is etched, are seen in 
 slight relief. The portions between these bands are granulated, 
 (fig. 7 />.) 3Iore compact calcareous portions are however met 
 with, and these are penetrated by delicate tufts of tubuli like 
 those of Kozoon, (lig. 7 c,) and arc adherent to the serpentine 
 p(n'ti()iis, which have nearly the sanio form as in the Eozoon 
 of Htoinhag, but are far smaller, (fig. 7 d.) In decalcified 
 specimens, they are found to possess the same arched walls as the 
 E<izoon. Their breadtli in the cross section is generally about one 
 tenth, and the diameter of the casts of the tubuli only about one 
 hundredth of a millimeter. These broader serpentine portions 
 are generally connected with a:, adjacent portion of lanicllx\ (also 
 composed of serpentine, or of a whitish mineral,) which are not 
 more than one-half their size, curiously curved, and presenting 
 highly arched and deeply incurved outlines, as may be seen in 
 decalcified specimens, (fig. 7 c) The study of these structures 
 leaves no doubt vhat they are due to an organism belonging to the 
 same group as the Eozoon. In order however to distinguish this 
 distinctly t-maller form of the primitive clay-slate series, with its 
 minute contorted chambers filled with serpentine, from the typical 
 Eozouii Cdiutdense of the more ancient Laurentiau system, it may 
 be designated as Euzoon Bavaricuni. 
 
 I have moreover subjected to microscopic examination a series 
 of .specimens from the fame linicstone horizon iu the Fichtelgebirge, 
 which, unlike those described, showed no distinct foreign 
 
0T:MBEL — ON LAURENTIAN ROCKS. 
 
 17 
 
 ^ 
 
 niir**'.!!;,, although presenti'ig certain denHe portions which seemed 
 to indicate the presence of some foreign matter. These portions 
 however showed only a cellular structure, like that in the specimen 
 from Hohenberg, without any tubuli ; nor did etching succeed in 
 developing any structure in these wholly calcareous specimens. 
 When therefore carbonate of lime both constitutes the 8k(3leton, 
 and replaces the sarcode, ther. is evidently little hope of recognizing 
 those organic forms. If jiowever the flaky pellicles which remain 
 suspended in the acid after the solution of the lime, in these 
 almost wholly calcareous specimens, are examined, they present a 
 very great resemblance to the similar pellicles from the Eozoou 
 limestone of Steinhag, already figured, which have such a striking 
 resemblance to organic forms. The careful examination of tho 
 limestone from many other ports in the Fichtelgebirge, affords 
 evidence of organic life similar to those o" Hohenberg ; thus 
 tending more and more to fill up the interval between the 
 J^aurentian gneiss, and the primordial zone of the Lower Silurian 
 fauna. We may therefore reasonably hope that in the study of 
 these more ancient rock-systems, which geologists have only 
 recently ventured to distinguish, paleontological evidence will bo 
 found no less available than in the more recent sedimentary 
 formations. The inferences which we are permitted to draw ''rom 
 the discovex'y of organic remains in these ancient rocks, confirm 
 the conclusion to which I had previously arrived from the stuviy 
 of the stratigraphical relations, and the general character of these 
 ancient rock-systems ; viz., that there exists, in these ancient 
 crystalline stratified rocks, a regular order of progress determined 
 1)1/ the same laws which have ahead)/ been established for the 
 fornbatlons hitherto known as fossil if erons. 
 
 I cannot conclude this notice of the preliminary results obtained 
 in the investigation of the ancient Eozoon limestones of Bavaria, 
 without adding a few observations upon some foreign crystalline 
 limestones. It is well known that the crystalline minerals, which 
 in numerous localities are found in these limestones, often present 
 rounded surfaces, as if they had at one time been in a liquid state. 
 As examples of these, Naumann mentions apatite, chondrotite, 
 hornblende, pyroxene, and garnet. The edges and angles of these 
 are often rounded ; the planes curved or peculiarly wrinkled, 
 and only rarely presenting crystalline faces ; having in short a 
 half-fused aspect, and ottering a condition of things hitberto 
 unexplained. One of the best known instances of this is found in 
 
18 
 
 TIIR CANADIAN NATURALIST. 
 
 thn green hornblende (part^asite) from Parens in Finland. This 
 mineral there uceiirs in u crystalline liniostonc with lluor, apatite, 
 chondrotite, pyroxene, pyrallolite, mica and graphite; associations 
 very similar t') those of the serpentine of Steinhag. The grain.* 
 of pargasite, although completely crystalline within, and having a 
 l)erfect"cleavage, arc rounded on the exterior, curved i-.iward and 
 outward, and also approximatively cylindrical in form; so that 
 they may be best compared with certain vegetable tubercles. If 
 the crystalline carbonate of lime which accompanies the pargasite 
 is removed by an acid, there remains a mass of pargasite grains, 
 generally cohering, and presenting a striking reseniblancc to the 
 skeleton obtained by Mibniitting the Kozoon serpentine-limestone 
 to a similar treatment. The tubercles of nargasite arc then seen 
 to be joined together by short cylindrical projections, which are 
 however readily broken by pressure, causing the mass to separate 
 into detached grains. The highly crystalline and ferruginous 
 carbonate of lime vhich is mingled with the pargasite, shews no 
 organic structu-e either when etched or examined in thin sections; 
 although the pargasite presents forms similar to those observed in 
 the serpentine of Steinhag. The surfaces of the curved cylindrical 
 and tuberculated grains of pargasite are in part naked, and in part 
 protected by a thin white covering. In some parts fine cylindrical 
 growths arc observed, and in others cylindrical perforations passing 
 through the grains of pargasite. By a careful microscopical 
 examination of the surface of these grains (PI. T., fig. 8), 
 numerous small tubuli, sometimes two millimeters in length, are 
 clearly seen, and by their exactly cylindrical form may be readily 
 distinguished from other pulverulent, fibrous and acicular crystal- 
 • line mineral m. *ers. These cyh idcrs consist of a white substance, 
 which contrasts with the dark green pargiisite, and have the 
 aiannt.',!- u'the tub' 1^ ..i'Eozoon, or from nh toiUi^ millimeters. 
 A single large cylinder was also observed lying obliquely across 
 between two of the pargasite tubercles. (PI. I., fig. 8 a.) In 
 the decalcified specimens, a white minerii" probably scapolite, was 
 observed side by side with the green parga.^ite; sometimes forming 
 groups of tubercles like the latter ; while in other cases a single 
 tubercle was found to be made in part of the green and partly of 
 the white mineral. From these observations there can scarcely 
 remtiin a doubt that these curious!, rounded grains of pargasite 
 imbedded in the crystalline limestone of Pargas represent the 
 casts of sarcode-chambers, as in the Eozoon ; and that they 
 
 t 
 
OUMBEL — ON LAURENTIAN R0CK8. 
 
 19 
 
 t 
 
 are conRequently of orj^anic origin. From the great similarity 
 between the forius of the pnrgasito graitm and the Kozoon- 
 Herpentine, \vc may liiirly bo pornnttod to issumo the preaonee of 
 Eozoon in the cryntulline linie.-<tones oi" Kinlaiul/f^ 
 
 Simihu- rehitions are doubtU'ss to be met with throuyhout the 
 cryHtalline limestones of Scandinavia, wherever sucli mineral 
 species occur in rounded grainn or in tuberculated forms. Tlie 
 notion that these forms are of organic origin, and have been 
 moulded in the spaces leit in a calcareous skeleton by the decay of 
 animal matter, receives a strong su]<i< rt from the observations of 
 Nordenskiold and Hisehof. The former found in a tuberculated 
 pyrallolite, 6:38 per cent, of bituminous matter, besides 8-58 per 
 cent, of water ; tvhile Bitwhof states that the same mineral 
 beeonKW black when ignited, and when calcined in a glass tube, 
 gives off a clear water with ;i very offensive enjpyreumatic odor. 
 
 There may also be mentioned in this connection a phenomenon 
 which is probably related to those just described. Upon the 
 pyritous layers which occur in the Ilercynian gneiss near IJoden, 
 are found great quantities of grains of quartz, almost transparent, 
 and with a fatty lustre, which have in all eases rounded undulating 
 forms, precisely resembling the pargasite tuber-' -■« from Finland. 
 Dichroite also sometimes occurs in this regie lu similar shapes, 
 although it also, in many eases, forms perfect crystals. The 
 evidence of organic forms may perhaps be found in these masses of 
 quartz and dichroite, though their treatment will necessarily 
 present difficulties. 
 
 A specimen of crystalline limestone, with rounded pyroxene 
 (coccolite) grains from New York, showed, after etching by 
 moans of acids, no traces of tubuli ; but the grains of . coolite, 
 remaining after the entire removal of the carbonate of lime, 
 were found to be connected with each other by numerous fine 
 cylindrical tubuli and skin-like laminae. The surface of the 
 rounded coccolite grains was much wrinkled, and studded with 
 small cylindrical processes of a white mineral, ijiometinies r: lifyirg, 
 and apparently representing the renmants of a system of tubuli 
 which had been destroyed by the crystallization of the carbonate 
 of lime. The flaky residue from the solvent action of the acid 
 exhibits, under the microscope, laminae, needles, and strings of 
 
 * These belong to the primitive gneiss formation of Scandinavia, 
 which the geologists of Canada, so long ago as 1855, referred to the 
 Laurentian system.— T. S. H. 
 
 I 
 
20 
 
 THE CANADIAN NATURALIST. 
 
 I 
 
 globules Kiir.iliir to those described in the residue from the 
 Eozoon ophicalcite of Steinhng, with which, and with the 
 hornblendic liuu'stoiie of Pargas, this eoccolitc-bearing limestone 
 if 2Sew York seems to be closely related. 
 
 A fragment of ophicalcite from Tunaberg in Sweden bears ti 
 stnknm- resemblance to the coarser marked varieties of this rock 
 from near l^issau. The carbonate of lime between the tubuli is 
 very sparry ; and after its removal, a perfectly coherent serpentine 
 skeleton is obtained, as in the Passau specimens. The surface of 
 the serpentine tubercles is abundantly covered with acicular 
 crystalline needles of various lengths, whose inorganic nature is 
 unmistakei'ble. The sediment from the acid solution also contains 
 a prodigious (piantity of these same small crystalline needles. On 
 etching a specimen of this rock with dilute acid, the same needles 
 were found in most places ; but luu-e ami there, in isolated, less 
 crystalline and more solid portions of the carbonate of lime, there 
 were seen curved and ramified tubuli, undoubtedly corresponding 
 with the tubuli of Eozoon, and having the same size and manner 
 of grouping as in the Eozoon of Passau. The ophicalcite of 
 Tunaberg is therefore to be classed with the Eozoon-beariug 
 
 limestones. 
 
 A specimen of crystalline limestone from Boden in Saxony, 
 holdinu' rounded grains of chondrodite, hornblende and garnet, and 
 furnished me by Prof. Sandberger, showed, after etching, tubuli of 
 surprishig beauty, both singly and in group.,,, but only in small 
 isolated compact portions of the carbonate of lime. The sparry 
 crystallization of this mineral seems to have frcfjuently destroyed 
 the cohesion of the very delicate tubuli, the fragments of which 
 may be observed in very -irge quantity in the flaky residue from 
 
 the solution. 
 
 A blackish serpentine limestone from Ilodrisch in Hungary, 
 showed by etching no traces of tubuli. The granular residue from 
 its solution in acids showed under the microscope large quantities 
 of cell-like granules, with a central nucleus, and generally joined 
 in pairs, like the spores of certain lichens. More rarely however 
 three or four of such grains were joined together. By far tlie 
 greater part of them were of one and the same size, althougli 
 occasionally others of double size were met with. Their regularity 
 of form is much in favor of their origin from organic structure. 
 
 A fratrment of ophicalcite from Reichenbach in Silesia, whicli 
 Prof. Beyrich kindly furnished me, showed distinct parallel bands 
 
GUMBEL — ON LAURENTIAN ROCKS. 
 
 21 
 
 of serpentine with curved and undulatini,' outlines, resembling tlie 
 Eozoon ophiculcite of Canada. The etched portions show, in the 
 carbonate of lime between the serpentine, or in the interspaces of 
 the serpentine, the same relations as the limestone of llohcnberg 
 from the primitive clay-slate formation. The tubuli, which have 
 a certain resemblance with those of Hohenberg, are stuck together, 
 as if covered by an incrustation. Further examinations of this 
 limestone are required to determine more definitely the organic 
 nature of its enclosures. 
 
 A fragment of similar limestone without serpentine, from 
 Raspenau, shows not the remotest trace of any organic structure 
 whatever. The same negative results were obtained with a 
 specimen of granular limestone from Timpobepa in Brazil ; and 
 with a very coarsely crystalline carbonate of lime, holding 
 chondrodite, from Amity, New Jersey. These negative results 
 show that organic remains are sometimes wanting in the primitive 
 crystalline limestones, as well as in those of more recent for- 
 n.ations. The occasional absence from the primary limestones of 
 these regular structures is therefore an indirect argument for 
 their organic origin. 
 
 Explanation of the Plate. 
 
 Figure 1. Section of Eozoon Canadcn.se, with its serpentine replacement, 
 sliowinjr tlio fine tubuli and the canal-systcni, from the limestone of 
 Iho llercynian {i'liciss fo.jiiatiou at Steiuhag ; been by reflected 
 light, and uiaguilied 2") diameters. 
 
 2. Section of Eozoon from the limestone of Untcrsalzbach; 25 diameters. 
 
 ;{. Soetiim of Eozoon from tlie limestone of Bubing. 
 
 4. Section of Eozoon i'rom the limestone of Steinhag ; 120 diameters. 
 
 f), a and h. Knotted tubuli from the insoluble residue of the Steinhag 
 limestone; 'MM diameters. 
 
 6. a, I), c, and d. Flocculi from the same residue ; 4U0 diameters. 
 
 7. Section of Eoyion Bavaricum, with serpentine, from the crystalline 
 
 limestone of the Hcrcjmian primitive clay -state formation at 
 
 IToheuberg ; 25 diameters. 
 a. Sparry carbonate of lime. 
 h. Cellular carbonate of lime. 
 c. System of tubuli. 
 
 <■/. Serpentine replacing the coarser ordin.i rariety. 
 r. Serpentine, and hornblende, replacing liio finer variety, in the 
 very much contorted portions, 
 
 8. Aggregated grains of pargasite, remaining after the solution of the 
 
 carbonate of lime, from the gruimlar limestone rock of Pargaa.